Yesterday’s news, of course, and a surprising development “locally” where measurable rain during the day seemed remote, at least at 6 AM yesterday. But, a blob of rain moved in around noon and gave out 0.06 inches. We’ll take it.
And as you all know, much more rain from our tropical system off Baja is just ahead, U of AZ mod says beginning late tonight and continuing into most of tomorrow morning as you can see here. If you want to see the forecast rain/snow in all of Arizona pile up over time, go here (from the U of AZ). The model is thinking between 0.25 and 0.50 inches here, an inch or so on top of Ms Mt Lemmon. Gut feeling is that we’ll see more than half an inch here from this, with a good chance that it will go beyond noon tomorrow when the mod thinks its all over. Hoping, anyway.
Below, amounts forecast by the U of AZ model ending at noon tomorrow. The model was run on data from last night at 11 PM AST.
Also yesterday, we had a very brief but fabulous sunrise “bloom” illuminating the bottoms of the thick Altocumulus clouds overhead. It looked something like this1: Hoping for same today.
7:23 AM. Year different from 2013.
In case you missed it, here’s what gray skies and light rain look like, falling of course, from that great steady rainmaker, Nimbostratus.
12:31 PM. “Two riders were approaching (under Nimbostratus), and the wind began to howl…”2 Well, OK, one rider. Note rain haze against Pusch Ridge and smoothness of sky due to precipitation fallout that obscures cloud detail. When you saw that smooth sky approaching from the SW, that was the time to turn your horse around and head for the barn, as here.
The rest of yesterday? Blasé. Steady diet of overcast Stratocumulus/Altocumulus clouds sometimes with splotches of virga, and a sprinkle here and there. Here’s pretty much what the rest of the day looked like:
2:01 PM. Two layers of Altocumulus are visible, the lower one on the S horizon beyond Pusch Ridge. Cloud detail (rumples and such) shows that there was no precipitation falling from these clouds. If someone asked you why, you’d say that the layer was not cold enough to produce ice crystals-snowflakes, things that would grow and drop out the bottom. The cloud droplets in these clouds are too small to fall, and even if they did float down and out, they’d be gone in a few seconds because they are so small.
4:46 PM. Creamy-looking Stratocumulus. Sometimes cloud bottoms look this way because of a moist layer overrunning dry and stable air, air that “raggifies” cloud bottoms and wind shear at cloud bottom can produce concave (inverted bowl-looking bases). TUS sounding at 5 PM shows air speed sped up a little at cloud base over wind just below them and wind direction turned about 10 deg from that just below cloud base. Was it enough? I guess so, but not really sure except by sky.
Rain still foretold for Sunday night into Monday morning, followed by a cold blast, but amounts have been on the decline. Could be just a few hundredths to a quarter inch is about all this one can produce.
Clouds today
More interesting scenes today of “multiple layers” as we would call them, and not as widespread as yesterday overall; Altocumulus (and with the wind picking up aloft, a lenticular here and there–look to the NE of Ms. Mt. Lemmon) Altostratus, Cirrus. And, with luck, a great sunset.
Way ahead…….
In the usual model vagaries, absent rain in them after this Monday for awhile, rain has shown up, beginning on the 4th of February. This is a new development in the models for that period. The NOAA spaghetti plots give this system pretty good support–that is, something is likely to approach the central and southern California coast a day or two before our possible “storm” on the 5th. but thereafter, not much confidence for a storm here. So, likely to be on the doorstep for us on Feb 3rd or so as it. Interestingly, it rains for two days off and on here, Feb. 4th and 5th, and the rain follows a trajectory from the Pacific much like we have today, which is always a good sign since the atmosphere likes to repeat itself. You can see the full sequence here.
TE
——————————-
1A replica of yesterday’s sunrise since Mr. Cloud-maven person’s camera failed to ingest a memory card prior to a dozen or so snappages. Camera acted like there was nothing wrong!
2That Dylan line would been that bit better, more dramatic, with “Nimbostratus” in it.
(From Dylan’s, “All along the Watchtower”, the best version, it goes without saying, performed by Seattle’s own Jimi Hendrix.)
“Cloudy/The sky will be gray and white and clou–oooowww–deee.”
If you don’t remember the 60s and songs about weather, a silly reprise of that Simon and Garfunkel song here. If S&G had been weather forecasters, they might have written satisfying lines like the one above for today.
At times today, with all the virga around, it might really look like its, “hanging down on me” as the two depressed boys sing in that song as waves of thick middle and high clouds eject northeastward over Catalina from the tropical Pacific. Looks like the heart of the upper level disturbance and its main rain shield will pass Friday night into Saturday, with a break in rain on Sunday, then rain again on Monday into Tuesday as the cold punch of this storm sequence rattles down from the north Pacific Coast. Great news, but not new news to anyone paying much attention to our local weather forecasts.
Catalina seems destined to get a good dumping from the two combined (the warm one, then the cold one), likely to exceed a half an inch, and boy, do we need it. Nothing after this in rain, the mods say (for now).
As a note in passing, the droughty Plains States don’t get so much relief from this system now as the models have faster movement of the storm through that region than they had a few days ago when it was part of a “trillion dollar” beneficial storm sequence across the country. That faster movement of the storm has been repeated in the mods now over and over. Faster movement equals less rain, less time for humid air from the Gulf of Mexico to race northward and be ingested into the low center that forms in the Plains States in a few days. I actually feel kind of sad seeing that change happen and hope its dead wrong. “Dang”, as we would say.
Yesterday’s clouds
Here are some shots of those great Cirrus clumps and formations yesterday some of which were exceptional because of the instability up there, that is, how tall and Cumulus-looking some of the Cirrus castellanus turrets got, biggest I’ve seen. You can reprise the whole day here, from the U of AZ. First, a shot of the great sunrise.
In the AZ movie, you will also see these brighter flecks appear, brighter because they have smaller, more numerous particles in them when they first form compared to even minutes later as they disperse. The behavior of CIrrus forming like this is like a puff of smoke that suddenly appears in the sky, but no more smoke is added. As happens with these Cirrus flecks, the smoke would gradually disperses and thins after a thick beginning.
Later in the movie, you’ll see the “convective” Cirrus we call castellanus go by, producing a little virga. Another oddity, is that some Cirrus uncinus trails go by with the streamers of ice that are falling out, go faster than the higher tuft from which they fell from, indicating a wind speed increase as you go down, a little unusual at that level.
So, lots to see in this time lapse movie.
7:18 AM. New flecks of Cirrus floccus-later to be Cirrus uncinus–form beyond Pusch Ridge. Lower Ci Spissatus in the distance.1:42 PM. Here, continuing with the innovative “gritty-not-pretty” photo style: “Cirrus castellanus slightly below Cirrus spissatus, both above parking area and partially occupied buildings.” $525
2:13 PM. Giant Cirrus castellanus turret springs from Cirrus streak. When they’re flattish, you’d call them Cirrus spissatus. If in more of a sky covering layer, sans breaks, Altostratus, not Cirrus, because of the shading. ONLY Ci spissatus can have shading and still be termed Cirrus.
3:48 PM. Mostly Cirrus spissatus (dense Cirrus).
3:48 PM. Just pretty Cirrus.
5:40 PM. Not a great sunset, as was hoped for, but there was a knife-edge leading edge of an Altocumulus bank on the far horizon that added some drama to it. Note Ci uncinus, too.
Watch for a sunrise color bloom this morning. Might happen, though coverage would appear to be a bit too much right now. And with so many clouds around, a good chance of a great one this evening. Charge camera battery.
——————
1There’s get a modicum of applause at the end of this video; no one really wanted to hear S&G play THAT song: “Why didn’t they play something good?” And, “Why are their heads floating around in the clouds?”
In case you like to go to the end first, a quite nice one:
5:53 PM. A mostly spissatus sunset.3:19 PM. Creepin’ Cirrus (spissatus) has creeped overhead.2:07 PM. Creepin’ Cirrus, creepin’ up from the south during the afternoon.
A little whirl in the air overhead and to our south now seems to have spawned some Altocumulus castellanus (Ac with vertical spires), according to nighttime sat imagery. Could be a very nice sunrise this morning, and because they’re going to be cold (colder than 0 F), likely to be some virga around, something that would really enhance the sunrise color.
It now appears the skies will clear completely later in the day as it passes by.
“In other news….” the tremendously cold air foretold in the models, supported by spaghetti, to ravage the East maybe ten days ago is now beginning to arrive. They’ll be some whining from back East (as in the next segment). Perhaps some folks in the East will now throw in the towel and finally decide to move to Arizona. Pretty sure some will.
A whiny, Seattle note: one of the HARDEST things to take when I lived there and biked to work for about 25 years, was the very pattern we have now with Seattle sitting under a HUGE, high amplitude bubble of warm air known as a ridge. The jet stream and storms are about as far away as possible in January from Seattle, and its nice and toasty along the West Coast IN GENERAL. Here’s a loop of the 500 mb maps (requires a lot of bandwidth). Below, the 5 AM AST map for this morning, illustrating the CLASSIC, “Warm in the West, cold in the East” one:
But not “warm in the West” for Seattle.
Fog forms in Puget Sound under these situations and the sun is too weak in all that clear warm air just a coupla hundred feet above you and often cannot burn off this shallow fog that you can see through a lot of the time!
And even if it does clear up, as it eventually did yesterday afternoon (time lapse there from just about where my Dept lab-office was), its still cold and clammy all day (yesterday it was 38 F in SEA with the sun out in the late afternoon). Sometimes the fog was so thin you feel like you could reach up and touch the warm air you knew, as a weatherman, was just above you.
So, like the last few days in SEA, you get foggy days, and “high” temperatures in the 30s, often with frost and ice on the roads in the mornings, so you can’t even bike to work in this “fair weather” pattern. It was tough to take because you had such a great chance for a sunny day with the storms pushed elsewhere, and it didn’t happen.
End of whine; glad to be in Arizona. I did love my job and my pals there in SEA, still do.
Rain still ahead here for the 28th; varies in amounts from model run to model run. Moisture from that storm now off Baja in the map above (its got lightning in it) will fiddle around out there until some westerlies “swooshes”1 the remains of that system this way late in the week.
Sadly, there appears to be no rain in sight for us after the 28th episode.
On a movie-sounding title theme again today, or this title could be the title of a bedtime story for kids, one that alludes to the Greek citizen bee keeper, Perlucidus, due to his early work in distributing hives, honey and honeycombs. Some cloud patterns resemble honeycombs, and so when Luke Howard decided to create a Latin system of names for clouds around 1802-03, he wanted to pay homage to Perlucidus1. Yesterday morning we had Altocumulus perlucidus and those clouds are discussed in detail below the lengthy “historic learning module” below.
——historic learning module————
Our Latin cloud naming system follows the tradition of Latin names first established in the hard sciences like botany and biology. After they did their naming thing, we weather folk decided, under leadership of Luke Howard, to “join the club”, to sound like the other scientists of the day when we were talkin’ clouds, that is, pretend to be on as solid a foundation as, say botanists, whom we likely envied, by creating a similar Latin naming system for clouds. That would show them!
Unfortunately, we really didn’t know what clouds had in them in those days, there were no aircraft measurements. Were they ice clouds or liquid droplet clouds, a mixture of both? And so the naming system that was developed came out a little fuzzy; flawed really. I guess “fuzzy” is appropriate for clouds. As the singer said, “I really don’t know clouds at all2.”
OK, after that “side lobe”…an example of fuzziness and flaws in our names: while Stratus and Altostratus have virtually the same name, and can look VERY similar on occasion, one (Stratus) is completely composed of droplets, and the other (Altostratus) is almost always completely composed of ice particles and snowflakes (aggregates of ice crystals, bunches locked together). No doubt Howard saw the visual resemblance from the ground, and may have thought they were composed of the same stuff.
Yet, from the name of Altostratus, you would think it is a droplet cloud like Stratus, but just located at a higher level (“alto” meaning “high” in Latin). Even our scientists confuse Altostratus in their peer-reviewed papers with something else because of this naming problem. A better name, since Altostratus is full of ice precipitation (unknown when Howard was making up his names, of course) would have been, “Altonimbostratus”. Nimbostratus, by definition, is a precipitating layer cloud, too.
Another problem in our naming system is that unlike in botany, where a redwood tree does not become a pine tree over time, clouds are always morphing into new forms.
And then we have to come up with silly expressions such as “Altostratus opacus cumulonimbomutatus”, what might pass for the remains of a Cumulonimbus cloud that has lost its base and only the heavy, higher level ice-cloud anvil (Altostratus) remains.
So, as Howard was attempting to follow the Latin scientific naming conventions of the day for clouds, up popped the descriptor, “perlucidus” for clouds patterned like a honeycomb in homage to Perlucidus1.
Two cloud genera (there are TEN3-I really like footnotes. They give a piece a really erudite feel even when its not), have the descriptor, perlucidus attached to them because they can attain a honeycomb pattern. These are Stratocumulus and Altocumulus, to repeat.
——-End of historic learning module———–
Yesterday we had some very cold Altocumulus perlucidus, some cloud elements shedding ice and disappearing because of it. The TUS morning sounding indicated these were in the range of -25 to -27 C. Here’s what these clouds looked like when they were still mainly composed of liquid droplets:
7:29 AM. Classic Altocumulus perlucidus (honey-combed pattern) with fine veils of ice crystals falling from many of the droplet cloud elements.
9:15 AM. Here, in brighter light, one can see the droplet clouds at left, while there are patchy, hazy regions in between. Those are the ice crystal remains, “ghosts” of the perlucidus cloud elements that have completely changed into ice (glaciated).
9:24 AM. Ovalized shot of the icy ghosts of perlucidus. There really is no cloud name for this grouping.
Strange Brew yesterday
There were also some very strange looking lower clouds as dry convection, associated with that little warming we had yesterday afternoon during this historic cold wave, bulged upward into a pretty moist laminar stable layer that resisted like heck being pushed up. When it was pushed up by that convection, which with greater moistness you would have seen as small Cumulus, instead you got slivers of clouds on top of where the Cumulus should have been. Those slivers of moist air that just reached the condensation level where droplets form in the air sliding over the top of the “invisible Cumulus.” The result, these odd forms shown below, resembling lenticular clouds with ragged bottoms in some cases:
12:15 PM. This dome shaped oddity. Was only there for a minute or two. Jumped out of car to get it. I hope your happy.12:38 PM. Then over the Catalinas, these strange forms of lenticularis clouds likely forced by dry convection rising up from underneath.
The last photo of a band of Stratocumulus with a ton of ice in it is worthy of a comment. A few days ago, the models had this day having significant precip, precip that would have been snow, followed by the same vast clearing we had later yesterday. Imagine last night and this morning’s cooling air augmented by a snow cover! Yikes. Woulda been 5 degree colder than what is already a pipe bustin’ cold morning. Wouldn’t have had so much afternoon melting because the ground has been chilled for several days now.
Wishing you happy pipes this morning. They’re freezing up here, temperature now 22.x here.
BTW, the list of Arizona low record temperatures will grow substantially today, as if you didn’t know it.
The weather ahead? Warmer. Can it be otherwise?
Also at 12:38 PM, looking farther down the Catalinas. Strange indeed.1:23 PM. The end of the clouds was at hand when this band heavily glactiating and higher-than-normal-based Stratocumulus clouds came over. (The elements were too large to be Altocumulus.) Some flurries could be seen falling from these clouds on Mt. Lemmon at little later.
The End
——-
1Shockingly, this part has been completely made up.
2She also said, “Ice cream castles in the air”, followed by, “Feathery canyons everywhere.” And finally, “Clouds got in my way.” (BTW, “Clouds got in my way”, too, as if you couldn’t tell!)
3The the ten are: Cumulus, Stratocumulus, Nimbostratus, Altostratus, Altocumulus, Stratus, Cirrus, Cirrostratus, Cirrocumulus, and the mighty most of the time, Cumulonimbus.
2:26 AM, Catalina: S- (light snow), 33.9 F, 0.01 inches so far. Precip not registering on Wunderground map site for some reason.
3:20 AM: S– (very light snow), 34.8 F. Temperature beginning to recover following precip, snow almost over, just a “skiff”, 0.3 inches.
6:20 AM: Total now a measly 0.02 inches, less than expected, but in keeping with jet “rule of thumb”; nil precip until 500 mb core goes by1, and its just getting here now–120 mph wind now at just around 18,000 feet over TUS, an extremely exceptional event for winds that strong to be that low!
Correction on storm total: Mr. Cloud Maven person forgot that when it snows, the small orifice into which the rain water usually flows without hesitation is clogged by that SNOW and the tipping bucket does NOT tip until the snow melts. It began melting in mid-morning, and by the time it was done melting, there was a total of 0.10 inches, 0.14 inches at the Sutherland Heights gage. This is a lot better than 0.02 inches.
County ALERT gage totals disappointing, too, just a few hundredths to a tenth of an inch; most with zeroes. Mountains reports missing since it fell as snow. (As with my own gage, the snow is melting into the buckets in the ALERT gages and they are now showing precip! )
(Here, the snow has melted and dribbled into the gage–NO it hadn’t!!!!) ((Shoulda looked inside the funnel before writing that!))
Only expecting small Cumulus today, but its cold enough that they could have some ice in them. It would be something for you to watch for.
Here’s the temperature and pressure traces for this dramatic cold front passage (FROPA) here in Catalina last night around midnight with the chart below beginning around 7 PM, this from a pitiful jpeg of computer monitor since the software I use will not print two parameters on the same graph (please fix this, Lightsoft Weather Centre, UK!):
You can’t read it, but the temperature dropped from 50.x F to 33.x F in about an hour, with period of very light snow, no accumulation at the end of that hour. And you can see what we meteorologists call a “pressure check” when a cold front goes by; starts rising immediately.
Yesterday’s clouds
Lots of lenticular formations around, beginning with this rosy specimen just downstream of the Catalinas at dawn:
7:17 AM. Altocumulus lenticularis downstream of the Catalinas.
Lenticular clouds downwind of the Catalinas persisted for hours yesterday. Its sometimes hard to tell that they are not over the mountains, but you can see that in the U of AZ time lapse for yesterday.
BTW, if you want to know how the UFO thing got started, legend has it that it was due to a hovering Altocumulus lenticularis cloud downstream of Mt. Rainier in the 1940s.
Viewing this U of AZ time lapse movie will tell you why lenticulars have sometimes been reported as UFOs. It really does look like a hovering “vehicle” in the morning hours in the movie, and a “hovering”, which is what we know alien spacecraft do; hover. In the face of the strong winds up there yesterday, hovering is, for most folks, unexpected, suspicious behavior. Check it out.
8:38 AM, below: CIrrus castellanus and floccus, i. e., “cumulocirrus”, Cirrus showing a lot of instability up there, steeper than usual decrease in temperature with increasing height. Makes things bubbly.
Finally, after the heavy mid-level overcast in the mid-late afternoon, a brief sunset bloom due to a distant clear slot beyond the horizon (way down at the bottom).
12:28 PM. Here’s comin’ at you, looking to the west; Cirrostratus way up top, below, Altocumulus lenticulars, and Cirrus spissatus (thick ice clouds possibly evolved from glaciating lenticular patches. Very complex scene. Thought about omitting it because what I couldn’t name and explain things?)1:02 PM. Altocumulus opacus invaded sky rapidly from the west. Bottom part looks pretty much like a lenticular, but it was scooting along, something true lenticular clouds don’t do. Hmmmm. Maybe I should omit this one, too.1:27 PM. ACSL is back again downwind of the Catalinas! (Altocumulus Standing Lenticular)
5:46 PM. A heavy layering of Altocumulus (opacus) is under lit by the sun for just a few moments. Like me, you may have initially given up on a “bloom”, but, by golly, it happened! BTW, as often happens, these heavy looking clouds were a lot higher than you might think, about 17,000 feet above Catalina (from the TUS sounding.)
What’s out there beyond the present cold spell and the warming after that?
This is kind of intriguing to me even though its kind of a waste of time, too. We’ll be reel cold for awhile, then it will suddenly warm up to seasonal temperatures for a few days. We know that. But then what?
Our models have been churning out wildly different forecasts toward the end of the month, and with those, wildly differing weather occurs here, naturally. These model forecasts are like a 5-foot wide puddle of water on a pot-holed street like the ones we have here in Catalina that they only repair in the most rudimentary way, throw some asphalt crumble in the hole, that its pretty much what they call a “repair.” Maybe its because we’re considered “po’ folk.” Let’s see, where was I? Oh, yeah, that puddle could be an inch deep or three feet deep. You just don’t know for sure.
One way to “dip stick” that “puddle” is in our NOAA spaghetti plots. At the end of this is the latest one from last night’s global data. You can see how wild (humorous) the forecasts are in the yellow and gray lines, indicating exactly opposite conditions in the West at the end of the month for those model runs at 00 Z (5 PM AST) and 12 Z (5 AM AST yesterday). Pretty bad.
The spag plot below from last night’s data suggest the warm ridge has the edge at this point (note clustering of blues lines to the northern US; red lines still confused). With a ridge holding forth, it would be a comfy time in AZ late in the month, not cold and blustery.
Valid for 5 PM AST January 25th.
Still, its not the final word, remembering that the atmosphere remembers. It will be interesting if it remembers enough to bust our venerable spag plots. That’s what makes it so darn interesting!
The End.
——————
1Its interesting that such an old style methodology, of the type used by forecasters before the rise of weather computing models, would seem to have equaled our best models in 2012.
Today, as everyone knows, will be the last pleasant day for quite awhile, so we’d better get out and enjoy it if you can, maybe call in sick. Likely to be a couple of AZ low temperature records set over the next week.
The skies will be great today, as they always are with some clouds present, and for a few days afterwards in the cold air with those deep blue skies along with passing Cumulus clouds, that at times and even though they are shallow, will send some virga down as the colder parts of the troughs go by. Should provide for some nice late afternoon and evening photo ops in the days ahead.
Today the satelllite imagery plus looking out the window, shows lots of Cirrus clouds today, probably devolving into dense, shady Altostratus at times. And a scenic, Altocumulus lenticularis cloud1 downstream from the Cat Mountains is pretty much a lock.
Also, in the progression of clouds today, we will probably see that clear slot that so often separates the middle and high clouds from the low, frontal clouds go by. If the timing of that clear slot is right, could be an extra special sunset.
Some Cirrus from yesterday, another one of those rarer days with virtually no contrails in the Cirrus, followed by a nice Catalina sunset:
2:36 PM. Cirrus fibratus (pretty straight fibers) looking NW. Note lack of contrails.5:45 PM. Cirrostratus fibratus (has streaks) with what looks to be a lower Cirrus uncinus (upper right and in the distance).
Rain, from the U of AZ mod run at 11 PM AST, has the rain beginning tonight after 10 PM AST and lasting but a couple of hours. Amounts here in Catalina, between 0.10 and about 0.40 inches, average of 0.25 inches, virtually no change from what was predicted 24 h ago.
Just about everything mentioned yesterday is the same today in the model, marginal cloud top temperatures for precip at the TUS site for most of the time the front goes by (in the model), but cloud tops will be colder over us and more likely to precip.
Seems temperatures will be marginal for ice-in-rain drops at the ground here since the much colder air will not arrive with the front’s very narrow rain band but encroach as it departs.
Also of some interest, the jet core at 500 mb is shown to become bifurcated with one branch overhead S as the rain moves in (another branch over NW AZ). This would be compatible with a rule of thumb about the rain and the jet at 500 mb. Rain, with extremely rare exceptions (<5% of the time), does not fall here on the southeast side of a jet stream racing to towards the NE, as we will have over us today. Will be curious to see if this “rule” holds up this time.
Tomorrow will be one of those cold days with spectacular small Cumulus clouds contrasted against the deep, dark blue of the winter sky. Should be some great scenes of light and shadows on the Catalina Mountains.
Snow ahead?
Snow falls here later in this cold, almost week-long episode, as a series of troughs plunge southward along the West Coast to AZ. Most likely day for some snowfall in Catalina, is now on the 14th2. Here’s the map for that, valid for 11 AM AST, Monday, from IPS MeteoStar:
Green areas denote those regions where the model has foreseen precip in the previous 6 h.
The weather way ahead–Dr. Jeckyl or Mr. Hyde?
Check out these bowl of rubber bands from “flapping butterfly wings” (slight perturbations put into the initial data ingested into the WRF-GFS model after which its re-run a number of times to see what slight differences do). The first one below is for the evening of January 20th, a real laugher considering its only 10-11 days away now and the mods are still clueless.
Note the yellow lines, a “control” run from last night’s 5 PM global data, and see how they BULGE toward the north over the western half of the US. Then look at the hard-to-see gray lines representing a “control” run from just 12 h earlier, that from yesterday’s 5 AM AST global data. They BULGE southward, the opposite way the yellow lines do.
The yellow lines indicate a huge ridge over the West, with little precip and seasonal temperatures in the SW US. On the other hand, the 5 AM control run shows a continuation of our present storm pattern and continued injections of cold air down the West Coast. Check out that gray line over northern Cal, for example.
So, from one model run to the next lately, our weather toward the end of the month in Catalina has gone from “yawn” to “yikes” (the latter blurted out yesterday when I saw that 5 AM output and all the storms it had). But blurted out a “yawn” when viewing the output from last evening. No precip after the cold week.
However, in deciding which of those two outcomes is most likely you have to dwell on the predominance of those blue lines that also bulge northward and are mainly located in southern Canada. Those strongly indicate that the “highs” , the bulges to the north over the western US, will prevail on the 20th, not the storms and cold weather with them.
Arrow points in the general direction of Arizona.
But how about after the 20th, at the very end of last night’s model run 15 days out? Now you see BOTH the yellow and the gray lines are bulging to the south (creating a trough bowl), AND, more importantly, those blue lines are not constrained to southern Canada, but are all over the West as well. Remembering that the atmosphere remembers suggests that the models are remembering, too, trying to regenerate the kind of flow pattern we’ve already been experiencing after a significant, quite pleasant, really, break from the cold week.
While this last panel is also a real laugher in many ways, due to all that uncertainty that’s indicated, the wildness in all those lines, you might want to hop off the fence in a longer term forecast toward the end of the month by thinking that what we’ve been having will return, a sort of “Back to the Future.”
Re-inforcing this view is how the red lines (570 dm height contours), usually on the periphery of the jet stream, become more compacted in the LATER, second plot compared with the first! This is a little remarkable since that would suggest the models have a better handle on the circulation pattern at 15 days over 11 days. Odd. Note, too, that those lines at 15 days are FAR to the south of AZ, supporting the idea of a cold trough in the SW.
———————————
1These are the almond shaped clouds composed of droplets with smooth, sharp edges that hover over the same spot, expanding and shrinking, sometimes for hours at a time, as the grade of moisture changes in the air being lifted behind the mountains.
2Personal aside: Have friend, former WA State Climatologist who also worked at the U of WA as I did, arriving here with his wife on the 12th for a vacation from the dark days of wintertime Seattle. They will be here for the whole cold week and possible snow as it turns out, and then go back. Having looked at the progs, he now wants to take a “vacation from his vacation”, maybe head off to Costa Rica after arriving in AZ!
Backdoor rain? Looks like any chance of rain will happen later this afternoon through overnight as mainly mid-level clouds twist around our low from the east. That low is now over Yuma, AZ, and the center will pass to the south of us tonight. We don’t see that happen too often. Here’s a nice loop of the circulation around it, also showing the radar echoes–very handy. (Some cloud shots at the bottom, way down there.)
Right now, our low is looking pretty dry, not much going on in it, or around it right now, and so any rain falling from mid-level cloud bands, like Altocumulus (with virga) and a likely deep band of Altostratus (also with virga), will be pretty light; sprinkles to maybe a hundredth or two. The better part of this is that with mid-level clouds coming from the east, they won’t be much dissipated by the air going downhill from the Catalina Mountains as you would expect with low clouds. However, in Mexico, since it is so cold in the center of this low, there will likely be reports of snow in unusual places, as in the last storm. The U of AZ Beowulf Cluster model, the best around for us, sees only a brief, fairly close call for rain tonight.
Still, while this low passage will be a little disappointing as far as rain goes, the skies will be great today with scattered Altocumulus, likely with a little virga, and scattered Cirrus, with a great sunset. Both of these cloud types can be very “photogenic” on days like this. Likely those mid-level clouds will clear out tomorrow morning, so get’em while you can. If you don’t, of course, this compulsive cloud photographer will.
Full cold ahead
Get ready for some terribly cold days just ahead, likely some snow in Catalina still, though the more moist Canadian model prediction for this storm has dried out overnight–tending to be more in line the with US models which have always had this cold wave as a light precip event. Precip is pretty much guaranteed here, and some snow probable in Catalina, but max and least precip totals from this storm have to be revised downward in view of the latest Canadian results. Minimum amount, 0.10 inches, max, 0.50 inches (was an inch due to how much offshore flow the prior Canadian models had the night before last). So, most likely amount is between those two extremes, or about 0.30 inches with precip beginning during the day on the 11th.
A further disappointment is that the mods now see this storm as a quickly moving event, and the precip is over by evening on the 12th, so it ends up as just a 24 h period of rain and snow chances, most coming, of course, in the first segment, a line of rain changing to snow with the frontal cloud band and wind shift line on Friday, the 11th. Dang.
What about the second cold blast on the 15th-16th?
Still coming, but this wiggle in the jet stream shooting down at us from the northwest, has a trajectory toward us that is farther east than it was shown in the models earlier, and the farther east and the further away the trajectory is from the coast, the drier these cold pushes will be. So, that second blast of cold air, while still looking very cold, is also looking pretty dry right now; may only get a passing snow flurry, or we’ll just see scattered small Cumulus with some virga.
In these latest model runs the jet stream pattern that has led to our “trough bowl”, the favored location where storms have been collecting in our region for the past month, begins shifting to the east at mid-month, and what’s more, the amplitude of the north-south oscillations in the jet stream fade to a more west to east flow.
This very different than what was depicted just the night before last. Here’s what I mean. Shown below is the first forecast panel, high “amplitude” pattern in the jet stream–always associated with temperature extremes, cold where the jet dips down, like HERE, and warmer than usual where it shoots up from the southwest,for example, there in Alaska.
Valid for the evening of January 15th. An example of “high amplitude jet stream configuration associated with temperature extremes.
This is a very common pattern. You probably remember how warm it was in Alaska during the 1962-63, and the 1976-1977 winters, but how friggin’ cold it was back East when this kind of high amplitude pattern was pretty extreme and persisted for weeks: the jet racing into Alaska from the mid-Pacific, and then shooting south into the US. Really horrible times for the East in those winters.
But look at what the model sees for the end of the 15-day forecast period, shown below! The jet hardly has any amplitude, just shoots in from the Pacific in a west to east flow. That means no temperature anomalies to speak of, and a moist West Coast regime, sometimes with precip getting this far south, too.
Valid the evening of January 22nd, a Tuesday.
What does spaghetti say about all of these changes?
Its pretty clueless, that is, slight changes in the observations make a big difference in what happens, and that’s why its so wild looking in the Pacific and the US (shown below). This means you probably can’t count on the above pattern a lot, except that the amplitudes have gone down, that seems to be a pretty solid expectation. That jet surging into AZ could just as well be intruding into Washington State in a west to east pattern. That would mean that our 30-days of below normal temperatures here in AZ, beginning in mid-December (shown here by the NWS, lower right panel), are about to end after about a week to ten days, and with that, a long dry spell likely to set in.
Yesterday’s clouds
Mostly Altostratus, thinning at times to Cirrus, and late, a few Altocumulus/Cirrocumulus patches. Here are a couple of shots.
7:22 AM. Under lit Altostratus at sunrise. Those little pouches are regions of light snowfall (virga).1:49 PM. Boring, generic Altostratus translucidus, an ice cloud. Sometimes droplet clouds like Altocumulus are embedded in them, but none can be seen here (they would be dark, sharp-edged flecks). The massive clearing that occurred in the late afternoon is visible on the horizon. If you saw that clearing, it would have been a great time to tell your friends that, “Oh, I think it will be sunny in 3 hours.” It would have been quite a magical moment for you.5:36 PM. This beauty of a patch of Cirrocumulus undulatus (tiny granulations in waves) and a lump of Altocumulus (lower left). TUcson sounding indicates they were about 15,000 feet above the ground at -20 C (-4 F). No ice apparent. It happens.
The above, a quote from Douglas Adam’s hypersupercomputer, “Deep Thought”, from the 1980s classic sci-fi radio series, “Hitchhiker’s Guide to the Galaxy”, spoken by DT as he prepares to give the answer to “life and everything.” In the context of the computing grandeur of DT, as one website quotes, “Don’t even mention these”:
The Milliard Gargantubrain
The Googleplex Star Thinker
The Great Hyperlobic Omni-Cognate Neutron Wrangler
The Multicorticoid Perspecutron Titan Muller
The Pondermatic
These still make you laugh from that classic NPR radio series-Eagles theme here).
I wanted to distract you with laughter if you are one of those persons who love Arizona or are a snow birdy solely because of its warm, sunny weather in winter. Not gonna happen this month1.
The answers to “weather and everything” below, and you’re not going to like them, unless you’re a skier, and you come to Arizona for great powder skiing!
By the numbers, what’s ahead:
Weather event 1. a little cut off low travels across northern Mexico from southern California bringing some fabulous-looking clouds today (high ones like Cirrus), and a brief shower at anytime tomorrow through Tuesday morning when its closest to us. Nice. But its not too cold yet. That comes later.
Rain in #1? Top pot (-ential): 0.25 inches; bot pot, just a trace. Most likely amounts hereabouts? A few hundredths to a tenth. Hoping for the development of a narrow, odd line of high-based (Altocumulus level) Cumulonimbus clouds that wrap around the upper low center as it goes by to south tomorrow. Wispy storms like this could produce little shower areas not conducive to model resolution at any time since the moisture threads running around it will be very narrow. You’ll have to be watching. Have camera ready for spectacular Ac castellanus (he sez) today and/or tomorrow.
In summary, today you will begin to be clouded over. On to event 2
Event 2, begins January 11th.
Summary: Yikes! Takes a few days to get through this. Check this prog out from Canada from last evening’s global data crunch (especially, the upper left and lower right panels):
Valid for 5 PM AST, Friday January 11th. “Totally awesome!” This new depiction moves this giant trough to offshore of southern Cal-Baja. You know that means. More water streaming north into AZ before the Big Cold hits, molecules of water vapor being sucked out of Pacific. That would be fantastic. One of the best model forecasts I have seen in a LONG time. Congratulations to Enviro Can for coming out with this last night. A real winner.
OK, quite exuberated over this Canadian forecast. For one thing, the dreaded super cold air is delayed, though it still happens after this big trough goes by. But mainly from this prog above, our precip potential is jacked up by twice with an upper level configuration like this, so much of it offshore now.
In the preceding days after Event 1 ends Tuesday morning on the 8th, the temperatures will rebound nicely, too, before the Big Whammy on the 11th-12th.
Rain in Event#2, January 11th (begins later in day)-13th? I think now you have to be thinking the “top pot” here in Catalina is 1.00 inches over a 48-72 h period, bottom pot, 0.30 inches (i.e., less than 10% chance of more; 10% chance of less). Median of these “best extreme guesses”, 0.65 inches. So, we got us another sure-fire substantial rain, even if the minimum is all we get. Go desert wildflowers!
Now, a caveat… US mods don’t have the flow as far offshore in event #2 as the Canadians do, thus, our mods have a much drier depiction for this storm. In these kinds of situations, no model has the complete truth, and so mentally you try to integrate the two. The lower precip bound of just 0.30 inches here is due to a compromise in actual flow patterns that might eventuate.
Quitting for a second to dream about pounding rain on the flimsy Arizona roof we got…the only kind to have if you’re a real CMJ (cloud maven junior); are a precipophiliac, as I am, or just like the sound of what the wildflowers are getting out there in the desert.)
Snow in Catalina in #2? Sure looks like it, toward the end of the precip, overnight 12th-13th. Will expeculate that 1-4 inches will fall between Saturday night into Sunday morning.
Event #3. The storms, though not nearly as moist as #2, troughs just keep “falling down the shoot” as the jet stream zips southward along the West Coast carrying storms to us for the foreseeable future with the timing of #3 on the evening of the 15th-16th (US WRF-GFS mod run from last evening’s data). Here’s what that cold trough and following blast of cold air look like on the evening of the 15th. A little snow is possible toward end of this event in Catalina, too. This goes by really fast, which is bad for precip totals, and “good” for extra cold air arriving here, since its shooting down at us so fast, that cold air can’t be modified much into warmer air as it goes southward.
Vallid for 5 PM AST, Tuesday, January 15th.
Only in the “dying embers” of last night’s model run, one that ends after 15 days, on the 21st, does it appear that there is a break in the pattern of below normal temperatures here. But, as we know, the atmosphere “remembers” for weeks at a time, so it may not be last long.
BTW, we are joined in cold air by our planetary neighbors in China, who are experiencing one of the coldest winters in 20-40 years. In a preliminary newsy item from China, they have attributed the cold winter to warming….and melting ice caps. Hmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm.
In an aside, should we see some really cold air, as is likely, the argument that “its colder because its warmer” may show up here. Its out there and I think it showed up after our February 2011 record freeze. Remember, I am a cloud-maven, not a climate-maven, but some statements do seem silly. Severe weather happens; always has, always will.
——————————–
1Its great, though, to see all those out-of-state license plates these days (Ohio, Ilinois, MN, PA, Iowa, ID, AK, Ontario, Can, seen just yesterday), knowing there are so many people who want to be where I am all the time, a permanent resident. I am sure all of us Arizona “barnacles” feel the same way!
The recording raingauge, that is. A coupla drops is all that fell here in Catalina after some indications of cores around us later yesterday afternoon that were producing measurable rain. You can go to the U of AZ rainlog site to see some local amounts–the Pima County ALERT site is down right now. They’ll have some reports in the mountains and elsewhere, providing it wasn’t snow. The most I’ve seen so far is 0.05 inches, lucky dogs.
Some nice cloud sights on a day of dramatic, icy development. I wonder if you say the first Cumulus/Stratocumulus blob glaciating far to the WSW, beyond Twin Peaks? I thought it would happen first toward the NW-N because the air got colder if you headed in those directions. Yesterday’s cloud highlights, once again pioneering here the “novella-sized”, explanatory caption:
8:24 AM. Altocumulus overspreads the sky, briefly. Ac perlucidus translucidus (thin). Someday I think I will make you memorize ALL of the cloud names and their species and varieties.8:59 AM. This beauty. It appears to be Cirrus of some kind (spissatus). But then yesterday I had written that there wasn’t going to be any Cirrus, and so I will term this, Altostratus translucidus altocumulotransmutatus. Pretty cloud, but ugly name (it really exists, and this patch really did originate via the glaciation of Altocumulus clouds.)10:33 AM. Never have seen this sequence before. After the prior patch of ice cloud (some liquid cloud at top) moved off, a new wedge of Altocumulus (perlucidus) formed in the moist plume up there. Also very pretty I thought. Estimated height above ground, 18,000 feet, -25 C or even a little colder. Nature loves to form water drops before it freezes, as here, even at very low temperatures.12:58 PM. Rise of the Cumulus machine…. Here, beyond Twin Peaks, is the first glaciating cluster of Cumulus/Stratocumulus responding to the cooling aloft and a bit of surface heating below.2:04 PM. Locally, our Cumulus remained small, but in the distance is the icy tops associated with the line of sprinkles its not drizzle that came through later in the afternoon, enhanced by further Cumulus deepening around here as the afternoon progressed. Pretty sky.2:38 PM. Heavier Cumulus bases line up against the Catalina Mountains near Charoleau Gap. Looking better for precip here at this point.
2:39 PM. A tell tale ice plume is amid these smaller clouds telling the observer that it is damn cold up there for such small clouds to produce so much ice (though the one that produced this little plume would have been taller than those around it) How cold? Estimate the top of the one that produced this was at least lower than -15 C (5 F). Ice crystal concentrations? Estimate at least a few per liter of air at this time when you see an ice plume like this. Pretty soon you’ll get that Cloud Maven tee.
3:58 PM. By this time it looked very promising for a few hundredths of rain.
5:36 PM. But after all the bluster, just a trace of rain here.
The weather ahead: measurable rain!?
I am sure, that due to our fine array of weather practitioners on TEEVEE (ones that make an incredible amount of money, mind-boggling really, and ones that have the same kind of fun doing weather forecasting as I do) that rain is in the offing for Catalina in the days ahead. So why bludgeon the topic here? Well, let’s guess a range of amounts that could occur, bottom and top, based on SOP-eyeball of weather patterns and goofy, variable progs:
Last night’s Canadian run, has a near miss now, rain partitioned to the SE of us. Booo! But, then rain with a follow up system on Jan. 1st, maybe with some snow in it here. So between the first threat and the second, both happening between the evening of December 30th and the evening of the 1st, the range has to be wild, maybe not useful. At the bottom, we could be completely bypassed in measurable rain from two strong troughs (we’re still in a “trough bowl” BTW), but I guess if you’re in a drought, you only get misses. But, being the optimist, AND with our own USA! model indicating measurable rain as of last night’s run, the range of amounts over the four days of chances, has to be from a trace to 0.50 inches at most. So, a range with all the factors at play is not too useful.
The average of those two, 0.25 inches, often works out as the closest estimate. Let’s see what the U of AZ has this morning… Oops, no update, budget cuts strike some more!
I guess I don’t need to blog after that title… We’ll be lucky to get 0.15 inches, and a few hundredths is the most likely amount, and that will fall later in the afternoon to late evening hours according to me and my (U of A Weather Department) model.
How much the U of A model thinks will fall regionally is seen for this event are seen in the panel below ending at 7 AM AST tomorrow morning, but first a caveat: I just saw this run for the first time now, and did not at first notice that it was OLD, from the night before last, not based on data from last night at 11 PM AST as usual. This lack of a model run might well be due to the effect of budget cuts noted on the link above… Dammitall, budget cuts!
Anyway, check the times of the run to make sure you’re not looking at something old today. I used it anyway because things have been well predicted in our incoming trough and jet stream for a couple of days now.
You can also see that with the jet over and just to the south of us later today through tomorrow morning, that most of the precip is to the north of the jet, as per usual in the interior of the SW1.
Here’s what the jet stream does in the next 18 h, starting with the forecast for 5 AM AST (these are from the latest data!). The winds are very strong over us now, but a core of strong winds is dropping down from California toward southern Arizona and reaches us later today and then drifts south. As that happens, the air aloft is really cooling off. The temperature at 18,000 feet (500 millibars) drops almost 10 F between 5 AM this morning and 11 AM!
As that happens, the air will be getting more moist from the bottom up. Small Cumulus will form later this morning and their tops will be rising and getting colder by the minute, eventually reaching our ice-forming temperatures around here of -10 C to -12 C, but tops to -20 C are likely late in the day. When ice begins form in these “supercooled” clouds, those crystals grow at the expense of the liquid droplets and fall out.
This cloud drama, if you will, is what makes today extremely exciting; watching for that first ice to form in these lower, relatively shallow clouds. They can be shallow and still develop ice because its so damn cold aloft later this morning and this afternoon.
So, a pretty if cold day, with lots of virga around later this afternoon, and with that, a great sunset is likely, too.
Yesterday’s clouds
10:03 AM. Your really cold Altocumulus clouds; transitioned to ice shortly after this. Probably colder than -25 C.1:32 PM. CIrrus spissatus, maybe it could be called an Altostratus translucidus since its quite thick toward the horizon.1:32 PM. You got yer Altocumulus lenticulars (brighter white clouds below patchy Cirrus.5:25 PM. The major band of high and some middle clouds exits south of Catalina. No high clouds today, only low and maybe some Altocumulus/Stratocumulus formed by the spreading out of Cumulus tops.
More rain in our future after later today and tonight?
Oh, yeah, baby. Its in the bag. A “virtual” certainty (which actually means its not absolutely certain at all, but that’s because its a weather forecast based on imperfect models and humans. Remember that great metaphor about why there’s an eraser at the top of a pencil? Profound.)
OK, when? Let’s start by looking to Canada for rain in Arizona: Here’s a panel from Enviro Can for Monday morning, December 31st at 5 AM AST. Its got rain in it, rain that would have fallen in the prior 12 h leading up to 5 AM. I like this model because it has more SE AZ rain in it than the US ones….
See lower right hand panel for rain in Arizona by the morning of the 31st.
There is a fly in the oinkment. The US models have a big “anti-cyclonic” bulge in the flow over us as our the trough/low approaches us on the 30-31st. These bulges in flow, toward the inner portion of the jet stream, can have devastating effects on clouds and precip formation. A bulge like that is like a high in a low; the effect is to weaken all the upward motions in the atmosphere. The Canadian model has less of that; hence, shows more rain here.
—————–
1Of course, if you have a copy Willis and Rangno (1971), “Final Report to the Bureau of Reclamation, 1970-71 Season, Colorado River Basin Pilot Project, Season 1”) you already know that.
